Slurry erosion behavior of two Zr-based bulk metallic glasses

Metallic glass, or named as amorphous alloy, is attracting in the engineering application as a wear resistance material since it has high hardness, yield strength, fracture toughness, and good corrosion resistance. Slurry erosion behaviors of the Zr-based bulk metallic glasses (BMGs) Zr55Al10Ni5Cu30 (Zr55) and Zr52.5Ti5Cu17.9Ni14.6Al10 (Vit105) were studied using sand-water two-phase flow. With the increase of impact angle, the volume loss rate of the BMGs roughly increased, indicating an erosion characteristic of brittle material. Compared with AISI 304 stainless steel, Vit105 reduced the erosion wear rate by about 35% at 30 degrees. The volume loss rate increased obviously with the impact velocity from 3.51 to 10.08 m s- 1. The relationship between the volume loss rate and the erosion time showed the volume loss rate of the BMGs dropped down after about 30 min erosion, suggesting a wear-in stage with strengthening wear resistance occurred. XRD patterns of these BMGs before and after erosion test illustrated the eroded Zr55 has no detectable crystallization, while some crystalline peaks presented at 10.08 m s- 1 and no obvious crystalline peaks presented at 3.51 m s- 1 in the patterns of Vit105. With the further DSC analysis, it can be concluded that the surface devitrification mainly depends on the impact velocity and BMG's thermal-stability. During the erosion, the variation of element concentration and the increase of oxygen content and oxides on the BMG surface indicated the mechanical degeration caused by sand particle was along with chemical degeration. With a higher ratio of hardness to elastic modulus (H/E), Vit105 shows better erosion wear resistance than Zr55. These work related to the wear-in stage of BMG with surface crystallization and element variation should be beneficial to improve the erosion resistance by the optimization of mechanical and thermal properties of amorphous alloys/coatings.